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Climate Change Vulnerability and Adaptation in the Blue Mountains Region

Chapter 4: Climate Change, Water Resources, and Roads in the Blue MountainsCaty F. Clifton, Kate T. Day, Gordon E. Grant, Jessica E. Halofsky, Charles H. Luce, and Brian P. Staab1

IntroductionWater is a critical resource in dry forest and rangeland environments of western North America, largely determining the distribution of plant and animal species across a broad range of elevations and ecosystems. Water is also essential for human endeavors, directly affecting where and how human communities and local economies have developed. The Blue Mountains of northeast Oregon and southeast Washington are an important source of water for forest ecosystems and human uses. Surrounding communities rely on water from national forest lands in the Blue Mountains for drinking water, industrial uses, irrigation, livestock watering, and recreation, among other uses. Climate change affects water supply by changing the amount, timing, and distribution of precipitation and runoff. These changes have the potential to affect water supply, roads and other infrastructure, and access to national forest lands in the Blue Mountains region. Reduced or less reliable water supply affects local economic activities, planning, and resource management. Dam-age to roads, bridges, and culverts creates safety hazards, affects aquatic resources, and incurs high repair costs. Reduced access to public lands reduces the ability of land managers to preserve, protect, and restore resources and to provide for public use of resources. Understanding vulnerabilities and the processes through which climate change affects hydrology will help U.S. Forest Service land managers identify adaptation strategies that maintain ecosystem function, a sustainable water supply, and a sustainable road system.

In this chapter, we (1) identify key sensitivities of water supply, roads, and infrastructure to changes in climate and hydrology; (2) review current and proposed management priorities, and share management approaches that already consider climate or climate change; and (3) use the latest scientific information on climate change and effects on hydrologic regimes (see chapter 3) to identify adaptation

1 Caty F. Clifton is the regional water quality and water rights program manager and Brian P. Staab is the regional hydrologist, U.S. Department of Agriculture, Forest Service, Pacific Northwest Region, 1220 SW 3rd Avenue, Portland, OR 97204; Kate T. Day is a hydrologist, Colville Forest Plan Revision Team, U.S. Department of Agriculture, For-est Service, 765 South Main Street Colville, WA 99114; Gordon E. Grant is a research hydrologist, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97331; Jessica E. Halofsky is a research ecologist, University of Washington, College of the Environment, School of Environmental and Forest Sciences, Box 352100, Seattle, WA 98195-2100; Charles H. Luce is a research hydrologist, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 322 East Front Street, Suite 401, Boise, ID 83702.

Climate change affects water supply by changing the amount, timing, and distribution of precipitation and runoff.

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GENERAL TECHNICAL REPORT PNW-GTR-939

strategies and tactics. During a workshop convened in La Grande, Oregon, in April 2014, participants reviewed the latest science on the sensitivity of water resources and related water uses and infrastructure to climate change in the Blue Mountains (boxes 4.1 and 4.2). Workshop participants worked collaboratively to identify adaptation options to reduce vulnerability to climate change and facilitate transi-tion to new conditions. The results of this vulnerability assessment and adaptation planning process are described in the sections below.

Water Resources and UsesIn the predominantly dry climate of the Blue Mountains region, water is the most critical natural resource for human habitation and enterprises. Many streams and groundwater systems surrounding the Blue Mountains region originate from the Malheur, Umatilla, and Wallowa-Whitman National Forests, thus providing a valued ecosystem service to local communities and economies. There are about 6,800 water rights on national forest lands in the Blue Mountains; 43 percent provide water for domestic livestock, 32 percent support instream flows, 9 percent are for wildlife, 5 percent are for irrigation, and 3 percent are for domestic uses (Gecy 2014). By volume, instream flows account for 75 percent of water rights, with irrigation and domestic uses each accounting for 1 percent by volume, and water for livestock accounting for 2 percent by volume (Gecy 2014). Six municipalities (Baker City, La Grande, Long Creek, Walla Walla, Pendleton, and Canyon City) rely directly on the national forests for municipal water supply. In addition, 20 smaller communities rely on surface or groundwater from the Blue Mountains forests for drinking water. There are 320 points of diversion (under a certificated water right) within the boundaries of national forests in the Blue Mountains that provide water for domestic use (Gecy 2014; e.g., see fig. 4.1).

Water is critical for livestock on national forests and surrounding lands, and consumption for this purpose is broadly dispersed across different ecosystems. About 42 percent of national forest land in the Blue Mountains is considered suit-able for sheep and cattle grazing, and grazing occurs on these lands in 455 of 552 subwatersheds within the Blue Mountains (Gecy 2014). Water for livestock is the largest permitted water use on national forest land by number of certificated water rights.

All basins in national forests of the Blue Mountains region are fully allocated in terms of water available for appropriation under state law in the dry summer season. In national forests, water is generally available for campgrounds and administrative sites and for other appropriated uses (e.g., livestock and wildlife),

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Box 4.1—Summary of climate change effects on water resource use in the Blue MountainsBroad-scale climate change effectDecreasing snowpack and declining summer flows alter timing and availability of water supply.

Resource entity affectedDrinking water supply for municipal and public uses both downstream from and on the national forests, other forest uses including livestock, wildlife, recreation, firefighting, road maintenance, and instream fishery flows. Change in availability of water supply to meet human uses increases the risk of scarcity and of not satisfy-ing consumptive and instream needs.

Current condition, existing stressorsAll basins are fully allocated in terms of water available for appropriation under state law. On national forests, water is generally available for campgrounds and admin-istrative sites and for other appropriated uses (e.g., livestock and wildlife), although in dry years, availability may be limited at some sites, especially in late summer. In drought years, downstream “junior” users may not receive water for various pur-poses, primarily irrigation. Six municipalities rely directly on the national forests for drinking water supply (Baker City, La Grande, Walla Walla, Pendleton, Long Creek, and Canyon City). Ecological effects include the following: onforest dams for storage facilities and stream diversions affect stream channel function; and development of springs and ponds for livestock affect many groundwater-dependent ecosystems. Changes in water supply are expected to influence water use by vegetation, exacer-bate low soil moisture, and influence fire frequency with various secondary effects on water supply and quality.

Sensitivity to climatic variability and changeRegional water supplies are highly dependent on snowpack extent and duration; April 1 snow water equivalent is the traditional indicator of late-season water avail-ability. Declining summer low flows will affect water availability during this period of peak demand (e.g., for irrigation and power supply).

Expected effects of climate changeDecreased snowpack extent and duration are expected to affect the timing and availability of water supply, particularly in late summer when demand is high for both consumptive and instream uses. Decreased summer low flows will limit water availability during critical times and for multiple uses.

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Box 4.1 continued

Adaptive capacityWithin-forest impacts will likely be less than downstream, although some facilities may see reduced water supply in late summer. Annual operating plans could be adjusted to limit potential for effects on streams and springs by permitted livestock and wildlife during dry years. Off-forest effects may be greater; although some municipalities have backup wells, and water supply for drinking water and other uses is likely to be affected. There is a need for coordination at the county and state level for conservation planning. There may be an increase in proposals for groundwater and surface storage development.

Risk assessmentPotential magnitude of climate change effects

• For those watersheds determined to be sensitive ○ Moderate magnitude by 2040 ○ High magnitude by 2080

Likelihood of climate change effects• For those watersheds determined to be sensitive

○ Moderate likelihood by 2040 ○ High likelihood by 2080

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Box 4.2—Summary of climate change effects on roads and infrastructure in the Blue MountainsBroad-scale climate change effectIncrease in magnitude of winter/spring peak streamflows.

Resource entity affectedInfrastructure and roads near perennial streams, which are valued for public access.

Current condition, existing stressorsMany kilometers of roads are located close to streams on the national forests, and these roads have high value for public access and resource management. A large backlog of deferred maintenance exists because of decreasing budget and mainte-nance capacity. Many roads are in vulnerable locations subject to high flows.

Sensitivity to climatic variability and changeRoads in near-stream environments are periodically exposed to high flows. Increased magnitude of peak flows increases susceptibility to effects ranging from minor erosion to complete loss of the road prism, resulting in effects on public safety, access for resource management, water quality, and aquatic habitat.

Expected effects of climate changeProjections for increased magnitude of peak flows indicate that more kilometers of road will be exposed to higher flow events and greater impacts.

Adaptive capacityKnowing the extent and location of potentially vulnerable road segments will help with prioritizing scarce funding, targeting “storm damage risk reduction” treatments, and communicating potential hazard and risk to the public.

Risk assessmentPotential magnitude of climate change effects• For those watersheds determined to be sensitive

○ Moderate magnitude by 2040 ○ High magnitude by 2080

Likelihood of climate change effects• For those watersheds determined to be sensitive

○ Moderate likelihood by 2040 ○ High likelihood by 2080

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Figure 4.1—Water right points of diversions (PODs) in the name of the Forest Service and in the name of others on and near the Wallowa-Whitman and northern Umatilla National Forest. The PODs in the name of the Forest Service represent a minor percent-age of consumptive water rights. Consumptive water rights in the name of others are con-centrated off forest in the Umatilla, Walla Walla, Grande Ronde, and Wallowa Valleys.

although in dry years, availability may be limited at some sites, especially in late summer. Dams for storage facilities, stream diversions, and development of springs and ponds for livestock on the national forests affect hydrologic and ecologic function of groundwater-dependent ecosystems (see chapter 7). In drought years, downstream “junior” users in the water allocation system may not receive water for various purposes, primarily irrigation. It is uncertain if long-term climate change or short-term drought will alter permitted water use in the future, although significant changes in water use during the next decade or so are unlikely.

Climate Change Effects on Water UsesWarming temperatures will lead to decreased snowpack and earlier snowmelt, resulting in shifts in timing and magnitude of streamflow and decreased summer soil moisture (see chapter 3). Across the Blue Mountains, the majority of precipita-tion occurs during the winter months, when consumptive demand is lowest. In summer, when demand is highest, rain is infrequent and streams are dependent on groundwater to maintain low or base flows. Because water supply in the Blue

In drought years, downstream “junior” users in the water allocation system may not receive water for various purposes, primarily irrigation.

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Mountains is limited, climate change may reduce water available to meet current demands in the summer months, especially during extreme drought years and after multiple consecutive drought years. Although current conflict over water use in the Blue Mountains is not a prominent issue, future water shortages may create social and political tensions as different sectors (e.g., agriculture and municipal) compete for scarce water.

Regional water supplies depend on snowpack extent and duration, and late-season water availability (often characterized by April 1 snow water equivalent). Declining summer low flows caused by earlier snowmelt runoff could affect water availability during peak demand. Historical snowpack sensitivity (fig. 4.2) and projections of summer steamflow (fig. 4.3) across the Blue Mountains identify areas that may be particularly sensitive with respect to water supply. Lower elevation locations with mixed snow and rain will be the most vulnerable to reduced spring snowpack, but even the most persistent snowpacks at higher elevation are expected to decline by the 2080s (see chapter 3). Variable Infiltration Capacity (VIC) hydro-logical model runs (for natural flows, not accounting for withdrawals, use, and storage) suggest that the Burnt, Powder, Upper Grande Ronde, Silver, Silvies, Upper John Day, Wallowa, and Willow subbasins are at highest risk for summer water shortage associated with low streamflow by 2080 (fig. 4.3). Decreases in summer low flows in these areas have the greatest potential to affect agricultural irrigation and municipal uses.

Water diversions and dams can also affect the resilience of watersheds to climate change. Although dams increase water storage during low flow, diversions also increase water extraction. Aging and inefficient diversion infrastructure can increase water loss. Engaging users within basins where water shortages can occur is critical for addressing water distribution and climate change effects. Clarifying water demand, negotiating water allocations, ensuring environmental flows in the water rights process, adjudicating over-allocated basins, and monitoring compliance can help reduce susceptibility to climate stresses.

Water quantity is an important attribute of the Watershed Condition Framework (WCF) classification system used by national forests to rate overall watershed condition (Potyondy and Geier 2011). Most subwatersheds across the Blue Moun-tains were rated as “functioning” or “functioning at risk” for this attribute, based on the magnitude of existing flow alterations from dams, diversions, and withdrawals relative to natural streamflows and groundwater storage. The Burnt, Powder, Upper Grande Ronde, and Wallowa subbasins have the highest number of subwatersheds rated as having “impaired function” for water quantity on national forest lands (fig. 4.4). Basins with the highest off-forest consumptive uses include Walla Walla,

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Umatilla, Burnt, Powder, Malheur, Silvies, and Silver Creek (Gecy 2014). Most of these areas are among those expected to experience the greatest changes in summer flows (fig. 4.3) and thus may be the most vulnerable from a water-use perspective.

Besides projected changes in streamflows and the magnitude of existing water diversions, the presence or absence of backup water systems is an important factor affecting the vulnerability of water supplies for human uses. Those systems with redundant supplies will generally be less vulnerable. Development of such systems, as well as increasing water conservation efforts, are key opportunities for adaptation.

Roads, Infrastructure, and Access Roads, trails, bridges, and other infrastructure were developed in the Blue Moun-tains over more than a century to provide access for mineral prospectors, loggers, hunters, and recreationists. The national forests in the Blue Mountains were created to protect water supply, timber, range resources, and wildlife, and to provide mul-tiple uses and enjoyment by the public. Providing access to accomplish these objec-tives largely determined where these activities historically occurred. Today, reliable and strategic access is critical for people to recreate, extract resources, monitor and manage resources, and respond to emergencies. Access to public lands promotes use, stewardship, and appreciation of their value as a vital resource contributing to quality of life (Louter 2006).

The three national forests combined contain 37 534 km of roads (table 4.1, fig. 4.5). Of the existing roads, 850 km of roads are paved, 17 800 km are gravel, and the remaining are native surface roads. Road density is higher at low elevations and adjacent to mountain passes, such as near major highways (fig. 4.5). Roads and trails cross many streams and rivers because of the rugged topography. Most

Table 4.1—Kilometers of road by maintenance level on national forests in the Blue Mountains

Operational maintenance levels (ML)

National forests

Code Description Malheur UmatillaWallowa-Whitman

KilometersML 1 Basic custodial care (closed) 6059 3543 7216ML 2 High-clearance cars/trucks 8814 3131 6719ML 3 Suitable for passenger cars 587 545 435ML 4 Passenger car (moderate comfort) 0 114 29ML 5 Passenger car (high comfort) 0 132 210 Total All roads 15 460 7465 14 609

Reliable and strategic access is critical for people to recreate, extract resources, monitor and manage resources, and respond to emergencies.

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Figu

re 4

.5—

Dis

trib

utio

n of

road

s and

trai

ls w

ithin

the

thre

e na

tiona

l for

ests

in th

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atio

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ontig

uous

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illio

n ha

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km

of r

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.

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(96 percent) known road-water crossings are culverts installed decades ago. Some crossings are being replaced, but many have not been inventoried and conditions are unknown. In many landscapes, the older the road, the more likely it is near or adjacent to streams, greatly increasing risks for road damage and degraded aquatic resources.

Historically, timber harvest was the primary purpose for development of the road system in national forests. Reduced harvesting during the past 20 years has decreased the need for roads for timber purposes. However, local population growth and tourism have increased demand for access for a diversity of recreation activi-ties. Hiking and camping are the most popular activities, but visitors are staying for shorter duration, often only day use; more than 60 percent of trips to national forests last 6 hours or less (USDA FS 2010). Short visits concentrate human impacts on areas that are easily accessible. Demand is increasing for trail use by mountain bikes and motorized vehicles and for routes designated for off-highway vehicles, as well as for winter recreation (USDA FS 2010).

Road Management and MaintenanceThe condition of roads and trails differs widely across the Blue Mountains, as do the impact of roads on watersheds and aquatic ecosystems. Culverts were typically designed to withstand a 25-year flood. Road construction has declined since the 1990s, with few new roads being added to the system. Road maintenance is primar-ily the responsibility of the Forest Service, but county road maintenance crews maintain some roads. The Federal Highway Administration is also involved with the management, design, and funding of roads within the national forests.

Roads vary in their level of environmental impact. They tend to accelerate runoff rates and decrease late-season flows, increase peak flows, and increase erosion rates and sediment delivery to the stream system. These impacts are gener-ally greater from roads closer to rivers and streams; however, roads in uplands also affect surface and shallow groundwater flows, and erosion processes (Trombulak and Frissell 2000).

Each national forest develops a road maintenance plan for the fiscal year, primarily based on priorities by operational maintenance level, then by category and priority. Maintenance of forest roads subject to Highway Safety Act stan-dards receive priority for appropriated capital maintenance, road maintenance, or improvement funds over roads maintained for high clearance vehicles. Activities that are critical to health and safety receive priority in decisions about which roads to repair and maintain, but are balanced with demands for access and protection of aquatic habitat.

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Given current and projected funding levels, national forest staff are examining tradeoffs between providing access and maintaining and operating a sustainable transportation system that is safe, affordable, and responsive to public needs, and that causes minimal environmental impact. Management actions being imple-mented to meet these sometimes competing objectives include reducing road main-tenance levels, storm-proofing roads, upgrading drainage structures and stream crossings, reconstructing and upgrading roads, decommissioning roads, converting roads to alternative modes of transportation, and developing more comprehensive access and travel management plans.

Planning for transportation and access on national forests is included in forest land management plans. The 2001 Road Management Rule (36 CFR 212, 261, and 295) requires national forests to use science-based analysis to identify a minimum road system that is ecologically and fiscally sustainable. The Malheur, Umatilla, and Wallow-Whitman National Forests are currently identifying a sustainable road network in accordance with the rule. The goals of transportation analysis are to assess the condition of existing roads, identify options for removing damaged or unnecessary roads, and maintaining and improving necessary roads without compromising environmental quality. Transportation analysis has four benefits: (1) increased ability to acquire funding for road improvement and decommission-ing, (2) a framework to set annual maintenance costs, (3) improved ability to meet agreement terms with regulatory agencies, and (4) increased financial sustainability and flexibility. Consideration of climate change is not currently a formal part of the analysis.

Major road projects in national forests, such as reconstruction of roads and trails or decommissioning, must comply with the National Environmental Policy Act (NEPA) of 1969 (NEPA 1969) and require an environmental assessment and public involvement. Decommissioning roads is a process of restoring roads to a more natural state by reestablishing drainage patterns, stabilizing slopes, restor-ing vegetation, blocking road entrances, installing water bars, removing culverts, removing unstable fills, pulling back road shoulders, scattering slash on roadbeds, and completely eliminating roadbeds (36 CFR 212.5; Road System Management; 23 U.S.C. 101).

Spatial and terrain analysis tools developed to assess road risks, such as the Water and Erosion Predictive model (Flanagan and Nearing 1995), the Geomor-phic Road Analysis and Inventory Package (GRAIP) (Black et al. 2012, Cissel et al. 2012), and NetMap (Benda et al. 2007), are often used to identify hydrologic impacts and guide management on projects. For example, the Wall Creek watershed GRAIP analysis on the Umatilla National Forest determined that 12 percent of the

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road system contributed 90 percent of the sediment, and focused treatment plans to the most critical sites (Nelson et al. 2010).

Climate Change Effects on Transportation SystemsAltered hydrologic regimes are expected as a result of climate change, especially in the latter half of the 21st century (see chapter 3). Specifically, climate and hydrol-ogy will influence the transportation system on Blue Mountains national forests through reduced and earlier runoff of snowpack, resulting in a longer season of road use, higher peak flows and flood risk, and increased landslide risk on steep slopes associated with elevated soil moisture in winter (Strauch et al. 2014). Increased wildfire disturbance (see chapter 6), in combination with higher peak flows, may also lead to increased erosion and landslide frequency.

Changes in climate and hydrology can have both direct and indirect effects on infrastructure and access. Direct effects are those that physically alter the opera-tion or integrity of transportation facilities. These include effects related to floods, snow, landslides, extreme temperatures, and wind. Indirect effects include second-ary influences of climate change on access that can increase threats to public safety and change visitor use patterns. For hydrologic extremes such as flooding, the effect on access may be more related to weather events (e.g., the effects of a single storm) rather than climate trends, but the expansion of future extremes outside the historical range of frequency or intensity will likely have the greatest impacts (e.g., by exceeding current design standards for infrastructure).

Projected changes in soil moisture and precipitation form and intensity with climate change may locally accelerate mass wasting in the Blue Mountains. For example, in the deeply dissected northern Blue Mountains, shallow rapid debris slides may become more frequent, impacting infrastructure and access. Climate projections indicate that the conditions that trigger landslides will increase because more precipitation will fall as rain rather than snow, and more winter precipitation will occur in intense storms (Salathé et al. 2014). These effects will likely differ with elevation, because higher elevation areas typically have steeper slopes and more precipitation during storms. Flooding can also be exacerbated by increased basin size during rain events, as snow elevation is projected to move higher, and thus more of the basin will receive precipitation as rain rather than snow. Further-more, reduced snowpack is expected to increase antecedent soil moisture in winter (Hamlet et al. 2013). Increasing trends in April 1 soil moisture have been observed in modeling studies as a result of warming, showing that soil moisture recharge is occurring earlier in spring and is now higher on April 1 than it was prior to 1947 (Hamlet et al. 2007).

Climate and hydrology will influence the transportation system on Blue Mountains national forests through reduced and earlier runoff of snowpack.

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Elevated soil moisture and rapid changes in soil moisture can affect the stabil-ity of a slope and are responsible for triggering more landslides than any other factor (Crozier 1986). Antecedent moisture, geology, soil conditions, land cover, and land use also affect landslides (Kim et al. 1991, Strauch et al. 2014), and areas with projected increases in antecedent soil moisture (coupled with more intense winter storms) will have increased landslide risk. Although the VIC (see chapter 3) model does not directly simulate slope stability failures or landslides, projections of December 1 total column soil moisture from VIC can be used as an indicator of landslide risk. Projections from VIC indicate that December 1 soil moisture will likely be higher as the climate warms, and thus there will be higher landslide risk in winter on unstable land types at higher elevations.

The vulnerability of roads to hydrologic change (see chapter 3) varies based on topography, geology, slope stability, design, location, and use. To assess vulner-ability of the transportation system in the Blue Mountains national forests, we identified the traits of the transportation system most sensitive to projected climate changes (box 4.3). This vulnerability assessment of the transportation system can inform transportation management and long-range planning.

Box 4.3—Sensitivities of the transportation system in national forests in the Blue Mountains• Aging and deteriorating infrastructure increases sensitivity to climate

impacts, and existing infrastructure is not necessarily designed for future conditions (e.g., culverts are not designed for larger peak flows).

• Roads and trails built on steep topography are more sensitive to landslides and washouts.

• A substantial portion of the transportation system is at high elevation, which increases exposure to weather extremes and increases the costs of repairs and maintenance.

• Roads built across or adjacent to waterways are sensitive to high stream-flows, stream migration, and sediment movement.

• Funding constraints, insufficient funds, or both limit the ability of agencies to repair damaged infrastructure or take preemptive actions to create a more robust system.

• Design standards or operational objectives that are unsustainable in a new climate regime may increase the frequency of infrastructure failure in the future.

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Roads and trails built decades ago have increased sensitivity because of age and declining condition. Many infrastructure components are at or near the end of their design lifespan. Culverts were typically designed to last 25 to 75 years, depending on structure and material. Culverts remaining in place beyond their design life are less resilient to high flows and bed load movement and have a higher likelihood of structural failure. As roads and trails age, their surface and subsurface structure deteriorate and less intense storms can cause more damage than a high-intensity storm would have when the infrastructure was new.

Advanced design of materials, alignment, drainage, and subgrade that are required standards today were generally not available or required when much of the travel network was developed in the Blue Mountains. Consequently, new or replaced infrastructure is likely to have increased resilience to climate change, especially if climate change is considered in the design. New culverts and bridges are often wider than the original structures to meet agency regulations and current design standards. In the past 15 years, many culverts across the Blue Mountains have been replaced to improve fish passage and stream function using open-bot-tomed arch structures that are less constricted during high flows and accommodate aquatic organism passage at a range of flows. Natural channel design techniques that mimic the natural stream channel condition upstream and downstream of the crossing are being used at these crossings. In addition, culverts on non-fish-bearing streams are being upgraded.

The location of roads and trails can increase vulnerability to climate change. Many roads and trails were built on steep slopes because of the rugged topography of the region, so cut slopes and side-cast material have created landslide hazards. Past timber harvesting and its associated road network in national forests have contributed to the sensitivity of existing infrastructure by increasing storm runoff and peak flows that can affect road crossing structures (Croke and Hairsine 2006, Schmidt et al. 2001, Swanston 1971). Many roads and trails were also constructed in valley bottoms near streams to take advantage of gentle grades, but proximity to streams increases sensitivity to flooding, channel migration, bank erosion, and shifts in alluvial fans and debris cones. Most road-stream crossings used culverts rather than bridges, and culverts are generally more sensitive to increased flood peaks and associated debris. Roads that are currently in the rain-on-snow zone, typically in mid-elevation basins, may be increasingly sensitive to warmer temperatures.

Management of roads and trails (planning, funding, maintenance, and response) affect the sensitivity of the transportation system, and the condition of one road or trail segment can affect the function of connected segments. Major highways within the Blue Mountains, built to higher design standards and maintained more

70


frequently, will likely be less sensitive to climate change than their unpaved coun-terparts built to lower design standards in the national forests. Lack of funding can limit options for repairing infrastructure, which can affect the short- and long-term vulnerability of the transportation system. For example, replacing a damaged culvert with an “in-kind” culvert that was undersized for the current streamflow conditions leads to continued sensitivity to both the current flow regime and projected higher flows.

Current and Near-Term Climate Change EffectsAssessing the vulnerability of the transportation network in the Blue Mountains to climate change (boxes 4.3 and 4.4) requires evaluating projected changes in hydro-logic processes (box 4.1). The integrity and operation of the transportation network in the Blue Mountains may be affected in several ways. Changes in climate have already altered hydrologic regimes in the Pacific Northwest, resulting in decreased snowpack, higher winter streamflow, earlier spring snowmelt, earlier peak spring streamflow, and lower streamflow in summer (Hamlet et al. 2007, 2010). Ongoing changes in climate and hydrologic response in the short term (in the next 10 years) are likely to be a mix of natural variability combined with ongoing trends related to climate change. High variability of short-term trends is an expected part of the response of the evolving climate system. Natural climatic variability, in the short term, may exacerbate, compensate for, or temporarily reverse expected trends in some hydroclimatic variables. This is particularly true for strong El Niño years (high El Niño Southern Oscillation index) and during warm phases of the Pacific Decadal Oscillation (as well as years with high Pacific Decadal Oscillation index), which may provide a preview of future climatic conditions under climate change.

Higher streamflow in winter (October through March) and higher peak flows, in comparison to historical conditions, increase the risk of flooding and impacts to structures, roads, and trails. Many transportation professionals consider flooding and inundation to be the greatest threat to infrastructure and operations because of the damage that standing and flowing water cause to transportation structures (MacArthur et al. 2012, Walker et al. 2011). Floods also transport logs and sediment that block culverts or are deposited on bridge abutments. Isolated intense storms can overwhelm the vegetation and soil water holding capacity and concentrate high-velocity flows into channels that erode soils and remove vegetation. During floods, roads and trails can become preferential paths for floodwaters, reducing operational function and potentially damaging infrastructure not designed to withstand inunda-tion. If extreme peak flows become more common, they will have a major effect on roads and infrastructure.

71


Box 4.4—Exposure of access to climate change in the Blue MountainsCurrent and short-term exposures (less than 10 years)• Roads and trails are damaged by floods and inundation because of mis-

matches between existing designs and current flow regimes.

• Landslides, debris torrents, and sediment and debris movement block access routes and damage infrastructure.

• Traffic is affected by temporary closures to clean and repair damaged roads and trails.

• Frequent repairs and maintenance from damage and disruption incur higher costs and resource demands.

Medium-term exposures (intensifying or emerging in about 10 to 30 years)• Flood and landslide damage will likely increase in late autumn and early

winter, especially in mixed-rain-and-snow watersheds.

• Current drainage capacities may become overwhelmed by additional water and debris.

• Increases in surface material erosion are expected.

• Backlogged repairs and maintenance needs will grow with increasing damage.

• Demand for travel accommodations, such as easily accessible roads and trails, is projected to increase, which could increase travel management costs.

• Increased road damage will challenge emergency response units, making emergency planning more difficult.

Long-term exposures (emerging in 30 to 100 years)• Fall and winter storms are expected to intensify, greatly increasing flood

risk and infrastructure damage and creating a greater need for cool-season repairs.

• Higher streamflows will expand channel migration, potentially beyond recent footprints, causing more bank erosion, debris flows, and wood and sediment transport into streams.

• Changes in hydrologic response may affect visitation patterns by shifting the seasonality of use.

• Shifts in the seasonality of visitation may cause additional challenges to visitor safety, such as increased use in areas and during seasons prone to floods and avalanches.

• Managers will be challenged to provide adequate flexibility to respond to uncertainty in impacts to access.

72


In the short term, flooding of roads and trails will likely increase, threatening the structural stability of crossing structures and subgrade material. Roads near perennial and other major streams are especially vulnerable (figs. 4.6 and 4.7), and many of these roads are located in floodplains and are used for recreation access. Increases in high flows and winter soil moisture may also increase the amount of large woody debris delivered to streams, further increasing damage to culverts and bridges, and in some cases making roads impassable or requiring road and facility closures. Unpaved roads with limited drainage structures or minimal maintenance are likely to experience increased surface erosion, requiring additional repairs or grading.

Increasing incidence of more intense precipitation and higher soil moisture in early winter could increase the risk of landslides in some areas. Landslides also contribute to flooding by diverting water, blocking drainage, and filling chan-nels with debris (Chatwin et al. 1994, Crozier 1986, Schuster and Highland 2003). Increased sedimentation from landslides also causes aggradation within streams, thus elevating flood risk. Culverts filled with landslide debris can cause flooding, damage, or complete destruction of roads and trails (Halofsky et al. 2011). Land-slides that connect with waterways or converging drainages can transform into more destructive flows (Baum et al. 2007). Roads themselves also increase land-slide risk (Swanson and Dyrness 1975, Swanston 1971), especially if they are built on steep slopes and through erosion-prone drainages. In the Western United States, the development of roads increased the rate of debris avalanche erosion by 25 to 340 times the rate found in forested areas without roads (Swanston 1976), and Chatwin et al. (1994) and Montgomery (1994) found that the number of landslides is directly correlated with total kilometers of roads in an area. Consequently, areas with high road or trail density and projected increases in soil moisture that already experience frequent landslides may be most vulnerable to increased landslide risks.

Short-term exposures to changes in climate may affect safety and access in the Blue Mountains. Damaged or closed roads reduce agency capacity to respond to emergencies or provide detour routes during emergencies. Increased flood risk could make conditions more hazardous for river recreation and campers. More wildfires (see chapter 6) could reduce safe operation of some roads and require additional emergency response to protect recreationists and communities (Strauch et al. 2014). Furthermore, damaged and closed roads can reduce agency capacity to respond to wildfires.

Short-term exposures to changes in climate may affect safety and access in the Blue Mountains.

73


Figu

re 4

.6—

Nat

iona

l for

est r

oads

loca

ted

with

in 9

0 m

of m

ajor

rive

rs a

nd st

ream

s. Th

ese

road

s, w

hich

are

con

side

red

vuln

erab

le to

incr

ease

d fl

oodi

ng, c

ompr

ise

3300

km

in

the

Blue

Mou

ntai

ns (9

40 k

m in

mai

nten

ance

leve

l (M

L) 1

[bas

ic c

usto

dial

car

e; c

lose

d], 1

915

km in

ML2

[hig

h-cl

eara

nce

cars

and

truc

ks],

377

km in

ML3

[sui

tabl

e fo

r pa

ssen

ger c

ars]

, 21

km in

ML4

[pas

seng

er c

ars;

mod

erat

e co

mfo

rt], a

nd 9

8 km

in M

L5 [p

asse

nger

car

s; h

igh

com

fort]

). N

ote

that

not

all

vuln

erab

le ro

ads a

re re

pres

ente

d;

som

e ro

ads a

lso

inte

rrup

t sm

alle

r int

erm

itten

t stre

ams a

nd v

ice

vers

a.

74


Figu

re 4

.7—

Proj

ecte

d pe

rcen

tage

cha

nge

in b

ankf

ull f

low

in 2

080

for r

oads

with

in 9

0 m

of a

maj

or ri

ver o

r stre

am (b

ankf

ull f

low

refe

rs to

the

flow

that

just

fills

the

chan

nel

to th

e to

p of

its b

anks

and

at a

poi

nt w

here

the

wat

er b

egin

s to

over

flow

ont

o a

floo

dpla

in. P

roje

ctio

ns w

ere

calc

ulat

ed u

sing

flo

w d

ata

from

the

Var

iabl

e In

filtr

atio

n C

apac

-ity

(VIC

) mod

el, b

ased

on

hist

oric

al d

ata

for 1

915–

2006

and

the

Q1.

5-ba

nkfu

ll or

cha

nnel

-form

ing

flow

sim

ulat

ed fo

r a g

loba

l clim

ate

mod

el e

nsem

ble

for t

he A

1B e

mis

sion

sc

enar

io (f

rom

Wen

ger e

t al.

2010

). N

ote

that

not

all

vuln

erab

le ro

ads a

re re

pres

ente

d; so

me

road

s als

o in

terr

upt s

mal

ler i

nter

mitt

ent s

tream

s and

vic

e ve

rsa.

75


Emerging and Intensifying Exposure in the Medium and Long TermMany of the observed exposures to climate change in the short term are likely to increase in the medium (10 to 30 years) and long term (greater than 30 years) (box 4.4). In the medium term, natural climatic variability may continue to affect outcomes in any given decade, whereas in the long term, the cumulative effects of climate change may become a dominant factor, particularly for temperature-related effects. Conditions thought to be extreme today may be averages in the future, particularly for temperature-related changes (MacArthur et al. 2012).

Flooding in autumn and early winter is projected to continue to intensify in the medium and long term, particularly in mixed-rain-and-snow basins, but direct- rain-and-snow events may diminish in importance as a cause of flooding (McCabe et al. 2007). At mid to high elevations, more precipitation falling as rain rather than snow will continue to increase winter streamflow. By the 2080s, peak flows are anticipated to increase in magnitude and frequency (fig. 4.8; see chapter 3). In the long term, higher and more frequent peak flows will likely continue to increase sediment and debris transport within waterways. These elevated peak flows could affect stream-crossing structures downstream as well as adjacent structures because of elevated stream channels. Even as crossing structures are replaced with wider and taller structures, shifting channel dynamics caused by changes in flow and sediment may affect lower elevation segments adjacent to crossings, such as bridge approaches.

Projected increases in flooding in autumn and early winter will shift the timing of peak flows and affect the timing of maintenance and repair of roads and trails. More repairs may be necessary during the cool, wet, and dark time of year in response to damage from autumn flooding and landslides, challenging crews to complete necessary repairs before snowfall. If increased demand for repairs cannot be met, access may be restricted until conditions are more suitable for construction and repairs.

In the long term, low streamflows in summer may require increased use of more expensive culverts and bridges designed to balance the management of peak flows with providing low-flow channels in fish-bearing streams. Road design regu-lations for aquatic habitat will become more difficult to meet as warming tempera-tures hinder recovery of cold-water fish populations, although some streams may be buffered by inputs from snowmelt or groundwater in the medium term.

Over the long term, higher winter soil moisture may increase the risk of land-slides in autumn and winter. Landslide risk may increase more in areas with tree mortality from fire and insect outbreaks, because tree mortality reduces soil root

76


Figu

re 4

.8—

Proj

ecte

d pe

rcen

tage

cha

nge

in Q

1.5-

bank

full

flow

in 2

080,

with

cul

vert

barr

iers

indi

cate

d ba

sed

on th

e ra

tio o

f cul

vert

wid

th to

ban

kful

l wid

th. P

roje

ctio

ns

wer

e ca

lcul

ated

usi

ng f

low

dat

a fr

om th

e V

aria

ble

Infi

ltrat

ion

Cap

acity

mod

el, b

ased

on

hist

oric

al d

ata

for 1

915–

2006

and

the

Q1.

5-ba

nkfu

ll, o

r cha

nnel

-form

ing

flow

, si

mul

ated

for a

glo

bal c

limat

e m

odel

ens

embl

e un

der t

he A

1B e

mis

sion

scen

ario

(fro

m W

enge

r et a

l. 20

10).

77


cohesion and decreases interception and evaporation, further increasing soil mois-ture (Martin 2006, Montgomery et al. 2000, Neary et al. 2005, Schmidt et al. 2001). Thus, soils will likely become more saturated and vulnerable to slippage on steep slopes during the wet season. Although floods and landslides will continue to occur near known hazard areas (e.g., because of high forest road density), they may also occur in new areas (e.g., those areas currently covered by deep snowpack in mid-winter) (MacArthur et al. 2012). Thus, more landslides at increasingly higher eleva-tions (with sufficient soil) may be a long-term effect of climate change. Coinciding exposures in space and time may be particularly detrimental to access.

Climate change effects on access may create public safety concerns for national forests. A longer snow-free season may extend visitor use in early spring and late autumn at higher elevations (Rice et al. 2012). Lower snowpack may lead to fewer snow-related road closures for a longer portion of the year, allowing visitors to reach trails and campsites earlier in the season. However, warmer temperatures and earlier snowmelt may encourage use of trails and roads before they are cleared. Trailheads, which are located at lower elevations, may be snow-free earlier, but haz-ards associated with melting snow bridges, avalanche chutes, or frozen snowfields in shaded areas may persist at higher elevations along trails. Relatively rapid warm-ing at the end of the 20th century coincided with greater variability in cool season precipitation and increased flooding (Hamlet and Lettenmaier 2007). If this pattern continues, early-season visitors may be exposed to more extreme weather than they have encountered historically, creating potential risks to visitors. In summer, whitewater rafters may encounter unfavorable conditions from lower streamflows in late summer (Mickelson 2009) and hazards associated with deposited sedi-ment and woody debris from higher winter flows. Warmer winters may shift river recreation to times of year when risks of extreme weather and flooding are higher. These activities may also increase use of unpaved roads in the wet season, which can increase damage and associated maintenance costs.

Climate change may also benefit access and transportation operations in the Blue Mountains over the long term. Lower snow cover will reduce the need for and cost of snow removal, and earlier snow-free dates projected for the 2040s suggest that low- and mid-elevation areas will be accessible earlier. Earlier access to roads and trails will create opportunities for earlier seasonal maintenance and recreation. Temporary trail bridges installed across rivers may be installed earlier in spring as spring flows decline. A longer snow-free season and warmer temperatures may allow for a longer construction season at higher elevations. Less snow may increase access for summer recreation, but it may reduce opportunities for winter recreation particularly at low and moderate elevations (Joyce et al. 2001, Morris and

More landslides at increasingly higher elevations (with sufficient soil) may be a long-term effect of climate change.

78


Walls 2009). The highest elevations of the Blue Mountains may retain relatively more snow than other areas, which may create higher localized demand for winter recreation and river rafting in summer over the next several decades.

Adapting Management of Water Use and Roads in a Changing Climate Through a workshop and subsequent dialogue, scientists and resource managers worked collaboratively to identify adaptation options that can reduce the adverse effects of climatic variability and change on water use and roads in the Blue Moun-tains. The workshop included an overview of adaptation principles (Peterson et al. 2011) and regional examples of agency efforts to adapt to climate change. Options for adapting hydrologic systems, transportation systems, and access management were identified, as well as potential barriers, opportunities, and information needs for implementing adaptation.

Adaptation Options for Water UseClimate change adaptation options for water use on national forests must be con-sidered within the broader context of multiownership watersheds, where most of the traditional consumptive uses occur off the forest but the forests are relied on for a majority of the supply. Many of the resource sensitivities addressed here already exist to some extent, but are expected to intensify as the climate warms. Adaptation options focusing on national forests were developed after consideration of the col-lective effects of several climate-related stressors: lower summer streamflow, higher winter peak streamflow, earlier peak streamflow, lower groundwater recharge, and higher demand and competition for water by municipalities and agriculture (table 4.2). The following adaptation strategies were developed to address these stressors: (1) restore function of watersheds, (2) connect floodplains, (3) support groundwater-dependent ecosystems, (4) reduce drainage efficiency, (5) maximize valley storage, and (6) reduce fire hazard (table 4.2). The objective of most of these adaptation strategies is to retain water for a longer period of time at higher elevations and in riparian systems and groundwater of mountain landscapes. These strategies will likely help maintain water supplies to meet demands, especially during the summer, and reduce loss of water during times when withdrawals are low. This diversity of adaptation strategies requires an equally diverse portfolio of adaptation tactics that address different biophysical components of hydrologic systems and timing of uses, among other considerations (table 4.2).

The adaptation tactic of using a “climate change lens” when developing plans and projects provides an overarching context for managing and conserving water

79


Tabl

e 4.

2—A

dapt

atio

n op

tions

that

add

ress

clim

ate

chan

ge e

ffec

ts o

n w

ater

use

in th

e B

lue

Mou

ntai

ns

Ada

ptat

ion

tact

icTi

mef

ram

eO

ppor

tuni

ties f

or

impl

emen

tatio

nB

arri

ers t

o im

plem

enta

tion

Info

rmat

ion

need

sSe

nsiti

vity

to c

limat

ic v

aria

bilit

y an

d ch

ange

: low

er su

mm

er fl

ows,

high

er w

inte

r pea

k flo

ws,

earli

er p

eak

flow

s, lo

wer

gro

undw

ater

rech

arge

, hig

her d

eman

d an

d co

mpe

titio

n fo

r wat

er b

y m

unic

ipal

ities

and

agr

icul

ture

.A

dapt

atio

n st

rate

gy: R

esto

re fu

nctio

n of

wat

ersh

eds,

conn

ect fl

oodp

lain

s, su

ppor

t gro

undw

ater

-dep

ende

nt e

cosy

stem

s, re

duce

dra

inag

e ef

ficie

ncy,

max

imiz

e va

lley

stor

age,

redu

ce fi

re h

azar

d.• A

dd w

ood

to st

ream

s and

incr

ease

be

aver

pop

ulat

ions

C

olla

bora

tion

with

oth

er a

genc

ies

Con

cern

s abo

ut e

ffect

s of

beav

ers o

n pr

ivat

e pr

oper

tyId

entifi

catio

n of

prio

rity

area

s

• Use

a “

clim

ate

chan

ge le

ns”

durin

g pr

ojec

t ana

lysi

sU

se th

e C

limat

e Pr

ojec

t Scr

eeni

ng

Tool

for a

naly

sis o

f pro

ject

s• I

mpr

ove

lives

tock

man

agem

ent t

o re

duce

wat

er u

se (e

.g.,

shut

off v

alve

on

stoc

k po

nds)

Som

e <1

0 ye

ars,

som

e >3

0 ye

ars

Col

labo

ratio

n w

ith ra

nge

man

ager

sM

inim

al te

chno

logy

ava

ilabl

e fo

r op

erat

ions

Impr

oved

tech

nolo

gy to

redu

ce

wat

er u

se

• Red

uce

surf

ace

fuel

s and

stan

d de

nsiti

es in

low

-ele

vatio

n fo

rest

<10

year

s, on

goin

gC

olla

bora

tion

with

fire

man

ager

sO

ppos

ition

to a

ctiv

e m

anag

e-m

ent,

pres

crib

ed b

urni

ng• R

esto

re m

eado

ws

Ong

oing

Inte

ract

ions

with

road

s El

k he

rbiv

ory

Inve

ntor

y an

d cl

assi

ficat

ion

of m

eado

ws

Ada

ptat

ion

stra

tegy

: Add

ress

dem

ands

for w

ater

(inc

ludi

ng w

ater

righ

ts);

impr

ove

wat

er c

onse

rvat

ion.

• Con

duct

inte

grat

ed a

sses

smen

t of w

a-te

r and

loca

l effe

cts o

f clim

ate

chan

geO

ngoi

ng,

oppo

rtuni

stic

Cas

e by

cas

eC

once

rns a

bout

pro

perty

righ

ts

Hig

h ex

istin

g w

orkl

oad

Upd

ated

wat

er re

sour

ce u

se

asse

ssm

ents

at p

riorit

y si

tes

• Im

plem

ent v

eget

atio

n tre

atm

ents

in

high

wat

er-r

eten

tion

area

s (e.

g., s

now

re

tent

ion)

Ong

oing

Enab

led

by n

atio

nal f

ores

t lan

d m

anag

emen

t pla

nLa

ck o

f fun

ding

for l

ong-

term

co

llect

ion

of g

age

data

Cen

traliz

ed so

urce

of d

ata

and

met

adat

a on

wat

er re

sour

ces

• Im

prov

e ef

ficie

ncy

of d

rain

age

and

ditc

hes

10 to

30

year

s

• Enc

oura

ge c

omm

unic

atio

n an

d fu

ll di

sclo

sure

of i

nfor

mat

ion

Ong

oing

Exis

ting

man

agem

ent p

lans

Iden

tifica

tion

of k

ey m

essa

ges

Com

mun

icat

ion

betw

een

line

offic

ers a

nd lo

cal c

omm

uniti

es• C

ondu

ct v

ulne

rabi

lity

asse

ssm

ents

by

com

mun

ity10

to 3

0 ye

ars

Sour

ce w

ater

ass

essm

ents

in so

me

case

s• T

reat

road

s whe

re n

eede

d to

reta

in

wat

er a

nd m

aint

ain

high

wat

er q

ualit

y<1

0 ye

ars

Col

labo

ratio

n w

ith ro

ad e

ngin

eers

Lack

of s

uppo

rt fo

r tre

atm

ents

Dev

elop

men

t of e

ffect

ive

road

tre

atm

ents

80


supply (tables 4.1 and 4.2). Including climate change in decisionmaking generally reinforces practices that support sustainable resource management. Potential risk and uncertainty can be included in this process by considering a range of climate projections (based on different models and emission scenarios) (see chapter 3) to frame decisions about appropriate responses to climate change. In addition, user awareness of vulnerability to shortages, reducing demand through education and negotiation, and collaboration among users can support adaptation efforts.

Many adaptation tactics to protect water supply are current standard practices, or “best management practices (BMP),” for water quality protection. In 2012, the Forest Service implemented a national BMP program to improve management of water quality consistently with the Federal Clean Water Act and state water quality programs (USDA FS 2012; http://www.fs.fed.us/biology/watershed/BMP.html). The BMPs are specific practices or actions used to reduce or control impacts to water bodies from nonpoint sources of pollution, most commonly by reducing the loading of pollutants from such sources into storm water and waterways. The BMPs are required on all activities with potential to affect water quality, including road management and water developments. A related tactic is improving roads and drainage systems to maintain high-quality water as long as possible within hydro-logic systems in national forests. Although these tactics may be expensive, they significantly affect water retention and erosion control. Actions are typically needed at specific locations at key times even under normal conditions, and climate change will likely force more frequent maintenance and repair.

Several adaptation tactics related to biological components of mountain land-scapes can reduce the effects of climate change on water resources. Reducing stand density and surface fuels in low-elevation coniferous forest reduces the likelihood of fires that severely affect soils, accelerate erosion, and degrade water quality in streams. Vegetation treatments in high-snow areas may enhance snow retention and soil moisture, and may extend water yield into the summer, at the catchment scale, for a few years following treatment.

Similarly, restoration techniques that maintain or modify biophysical proper-ties of hydrological systems to be within their presettlement historical range of variability can increase climate change resilience. Stream restoration techniques that improve floodplain hydrologic connectivity increase water storage capacity. Meadow and wetland restoration techniques that remove encroaching conifers can improve hydrologic function and water storage capacity. Adding wood to streams improves channel stability and complexity, slows water movement, improves aquatic habitat, and increases resilience to both low and high flows. Similarly,

81


increasing American beaver (Castor canadensis Kuhl) populations will create more ponds, swamps, and low-velocity channels that retain water throughout the year.

Lower soil moisture and low flows in late summer, combined with increasing demand for water, will likely reduce water availability for aquatic resources, recre-ation, and other uses. However, water conservation measures within national forests can potentially reduce water use. For example, resource managers can work with permitees to implement livestock management practices that use less water (e.g., install shutoff valves on stock water troughs). Over the long term, increasing water conservation and reducing user expectations of water availability (e.g., through education) are inexpensive and complementary adaptation tactics for maintaining adequate water supply.

At a broader level, it will be valuable to engage in and contribute to integrated assessments, such as the Oregon Integrated Water Resource Strategy, for water supply and availability and local effects of climate change. Vulnerability assess-ments for individual communities will provide better information on where and when water shortages may occur, leading to adaptation tactics customized for each location. Because discussions of water use and water rights are often contentious, it will be important to help foster open dialogue and full disclosure of data and regulatory requirements so that proactive, realistic, and fair management options can be developed.

Adaptation Options for Roads and InfrastructureClimate change adaptation options for roads and infrastructure were developed after consideration of the collective effects of several climate-related stressors: sensitivity of road design and maintenance to increasing flood risk, effects of higher peak streamflows on road damage at stream crossings, and safety hazards associated with an increase in extreme disturbance events (table 4.3, box 4.2). The following adaptation strategies were developed to address these stressors: (1) increase resilience of stream crossings, culverts, and bridges to higher streamflow; and (2) increase the resilience of the road system to higher streamflows and associ-ated damage by stormproofing and reducing the road system.

The Forest Service travel analysis process (USDA FS 2005) and BMPs provide an overarching framework for identifying and maintaining a sustainable transporta-tion system in national forests in the Blue Mountains, and climate change provides a new context for evaluating current practices (Raymond et al. 2014, Strauch et al. 2014). Incorporating climate change in the travel-analysis process, which is already addressing some vulnerabilities by decommissioning and stormproofing roads,

Vulnerability assessments for individual communities will provide better information on where and when water shortages may occur.

82


Tabl

e 4.

3—A

dapt

atio

n op

tions

that

add

ress

clim

ate

chan

ge e

ffec

ts o

n ro

ads

and

infr

astr

uctu

re in

the

Blu

e M

ount

ains

Ada

ptat

ion

tact

icTi

mef

ram

eO

ppor

tuni

ties f

or

impl

emen

tatio

nB

arri

ers t

o im

plem

enta

tion

Info

rmat

ion

need

s

Sens

itivi

ty to

clim

atic

var

iabi

lity

and

chan

ge: R

oad

desi

gn a

nd m

aint

enan

ce a

re se

nsiti

ve to

incr

easi

ng fl

ood

risk;

hig

her p

eak

flow

s lea

d to

incr

ease

d ro

ad d

amag

e at

stre

am c

ross

ings

(bec

ause

of i

nsuf

ficie

nt c

ulve

rt ca

paci

ty, m

ore

culv

ert b

lock

age,

and

low

brid

ges)

; saf

ety

is c

ompr

omis

ed b

y m

ore

extre

me

even

ts (e

.g.,

land

slid

es

and

debr

is fl

ows)

.A

dapt

atio

n st

rate

gy: I

ncre

ase

resi

lienc

e of

stre

am c

ross

ings

, cul

verts

, and

brid

ges t

o hi

gher

pea

k flo

ws.

• Rep

lace

cul

verts

with

hig

her c

apac

ity

culv

erts

or o

ther

app

ropr

iate

dra

inag

e (e

.g.,

ford

s or d

ips)

in h

igh-

risk

loca

tions

<10

year

s, op

portu

nist

icSt

ruct

ure

failu

res,

espe

cial

ly

at fi

sh c

ross

ings

Fund

ing

Cur

rent

bac

klog

of d

efer

red

mai

nten

ance

and

upg

rade

s

His

toric

al u

se p

atte

rns

Dat

abas

e of

pro

ject

s and

up

grad

es

Safe

ty p

riorit

ies

Cam

pgro

und

anal

ysis

• Com

plet

e ge

ospa

tial d

atab

ase

of c

ulve

rts

and

brid

ges

<10

year

s, op

portu

nist

icR

ecor

ding

of g

eosp

atia

l lo

catio

ns a

s pro

ject

s are

co

mpl

eted

Fund

ing

Inco

mpl

ete

culv

ert s

urve

y in

form

atio

n

Dat

abas

e of

pro

ject

s and

up

grad

es

Ada

ptat

ion

stra

tegy

: Fac

ilita

te re

spon

se to

hig

her p

eak

flow

s by

redu

cing

the

road

syst

em a

nd th

us fl

oodi

ng o

f roa

ds a

nd st

ream

cro

ssin

gs; d

isco

nnec

t roa

ds fr

om

stre

ams.

• Con

tinue

to d

ecom

mis

sion

road

s with

hig

h ris

k an

d lo

w a

cces

sO

ppor

tuni

stic

, >3

0 ye

ars

Partn

ersh

ips a

nd c

olla

bora

tion

with

oth

er a

genc

ies t

hat a

re

also

dis

conn

ectin

g ro

ads f

rom

w

ater

way

s

Hig

h co

st o

f de

com

mis

sion

ing

road

sIm

plem

enta

tion

of G

eom

orph

ic

Roa

d A

naly

sis a

nd In

vent

ory

Pack

age

for d

ecis

ionm

akin

g

• Con

vert

use

to o

ther

tran

spor

tatio

n m

odes

(e

.g.,

from

veh

icle

to b

icyc

le o

r foo

t)O

ppor

tuni

stic

, >3

0 ye

ars

Tran

spor

tatio

n pl

anni

ng, t

rave

l m

anag

emen

t pla

ns, l

and

and

reso

urce

man

agem

ent p

lans

Hig

h co

st o

f de

com

mis

sion

ing

road

s

• Inv

oke

Trav

el A

naly

sis P

roce

ss to

prio

ritiz

e ro

ad m

anag

emen

t<1

0 to

30

year

sTr

avel

Ana

lysi

s Pro

cess

and

M

inim

um R

oads

Ana

lysi

s are

un

derw

ay• U

se d

rain

s, gr

avel

, and

out

slop

ing

of ro

ads

to d

ispe

rse

surf

ace

wat

erO

ngoi

ng, 1

0 to

30

year

sN

atio

nal f

ores

t lan

d m

anag

emen

t pla

nH

igh

cost

of r

oad

man

agem

ent

Prio

ritie

s unc

lear

in so

me

case

s

Impl

emen

tatio

n of

Geo

mor

phic

R

oad

Ana

lysi

s and

Inve

ntor

y Pa

ckag

e fo

r dec

isio

nmak

ing

83


culverts, and bridges, will enhance resilience to higher streamflows. Improving and updating geospatial databases of roads, culverts, and bridges will provide a founda-tion for continuous evaluation and maintenance. If vulnerable watersheds, roads, and infrastructure can be identified, then proactive management (e.g., use of drains, gravel, and outsloping of roads to disperse surface water) can be implemented to reduce potential damage and high repair costs.

National forests in the Blue Mountains have a large backlog of culverts and road segments in need of repair, replacement, or upgrade, even under current hydrologic regimes. Limited funding and staff hinder current efforts to upgrade the system to current standards and policies, so the additional cost of upgrades to accommodate future hydrological regimes could be a barrier to adaptation. How-ever, extreme floods that damage roads and culverts can be opportunities to replace existing structures with ones that are more resilient to higher peak flows. These replacements, called “betterments,” can be difficult to fund under current Federal Highway Administration Emergency Relief for Federally Owned Roads program eligibility requirements when used to fix damage from extreme events, because the current policy is to replace in kind. In some cases, matching funds can be raised or betterments can be funded with sufficient justification and documentation of the environmental impacts. Justification for betterments based on the latest climate change science would facilitate this approach.

Increasing resilience to higher peak flows will not be possible for all road seg-ments because of limited funding for maintenance. Adapting road management to climate change in the long term may require further reductions in the road system. Road segments that are candidates for decommissioning are typically those with low demand for access, high risks to aquatic habitat, a history of frequent failures, or combinations of the three. National forest road managers also consider use of roads for fire management (fire suppression, prescribed fire, and hazardous fuel treatments).

Engineers may consider emphasizing roads for decommissioning that are in basins with higher risk of increased flooding and peak flows, in floodplains of large rivers, or on adjacent low terraces. Information on locations in the transportation system that currently experience frequent flood damage (Strauch et al. 2014) can be combined with spatially explicit data on projected changes in flood risk and current infrastructure condition to provide indicators of where damage is most likely to continue and escalate with changes in climate (e.g., figs. 4.7 and 4.8). Optimization approaches (e.g., linear programming) can be used to compare the tradeoffs associ-ated with competing objectives and constraints while minimizing the overall costs of the road system.

84


Reducing the road system in national forests presents both barriers and opportunities (table 4.3). Decommissioning roads or converting roads to trails is expensive and must be done properly to reduce adverse effects on water quality and aquatic habitat. Furthermore, reductions to the road system are often met with opposition from the public accustomed to using roads for recreational access, but public involvement in road decisions can also be an opportunity to increase aware-ness and develop “win-win” adaptation options. Thus, one adaptation tactic is to adjust visitation patterns and visitor expectations by actively involving the public in road decisions related to climate change. This has the added benefit of raising political support and possibly funding from external sources to help maintain access. Partnerships with recreation user groups will be increasingly important for raising public awareness of climate change threats to access and for identifying successful adaptation options.

Increased risk of flooding in some basins may require modification to current management of facilities and historical and cultural resources. In most cases, the high cost of relocating buildings and inability to move historical sites from flood-plains will require that adaptation options focus on resistance through prevention of flood damage. Stabilizing banks reduces risk to infrastructure, and using bioengi-neering rather than riprap or other inflexible materials may have less environmental impact. In the long term, protecting infrastructure in place will be more difficult as flood risk continues to increase. Long-term adaptation strategies may require removing (or not rebuilding) infrastructure in the floodplain to allow river channels to migrate and accommodate the changing hydrologic regime. National forest land and resource management plans, which have relatively long planning horizons, are opportunities to implement these long-term adaptation tactics for management of facilities and infrastructure.

More frequent failures in the road and trail system may increase risks to public safety. Limited resources and staff make it difficult for national forests to quickly repair damage, yet the public often expects continuous access. In response to cli-mate change, managers may consider implementing and enforcing more restrictions on access to areas where trails and roads are damaged and safe access is uncertain. Greater control of seasonal use, combined with better information about current conditions, especially during early spring and late autumn, before and after active maintenance, will ensure better public safety. Partnerships with recreation user groups may generate opportunities to convey this message to a larger audience, thus enhancing public awareness of hazards and the safety of recreation users.

In the long term, protecting infrastructure in place will be more difficult as flood risk continues to increase.

85


Managers may consider adapting recreation management to changes in visitor use patterns in early spring and late autumn in response to reduced snowpack and warmer temperatures. An expanded visitor season would increase the cost of oper-ating facilities (e.g., campgrounds), but revenue from user fees may also increase. Land management plans and transportation planning provide opportunities to address anticipated changes in the amount and timing of visitation. Limitations on staff because of funding or other constraints may also present obstacles to an expanded visitor season. Adaptive management can be used to monitor changes in the timing, location, and number of visitors, thus providing data on where manage-ment can be modified in response to altered visitor patterns.

AcknowledgmentsWe thank Robert Gecy, David Salo, and Thomas Friedrichsen for helpful discus-sions and contributions. We also thank all of the participants in the hydrology group at the La Grande workshop for their valuable contributions to this chapter.

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